Maybe the plot involves Naruto being sent to the dimension where Lady Phenex lives for some unknown reason. Lady Phenex is a very important figure in her world, and Naruto's sudden appearance causes a stir. At first, there's a lot of misunderstanding and Naruto has to prove that he means no harm. Eventually, they discover that there are some similarities between their powers, and they train together to become stronger. This new - found strength then helps them to save both of their dimensions from a great catastrophe.
A powerful demon lord could be the main antagonist. This demon lord might be after Lady Phenex's power, which is said to be able to control the very essence of fire. He sees Naruto as an obstacle in his path and tries to eliminate him first. The demon lord could have a legion of minions that Naruto and Lady Phenex have to fight through before they can face him directly.
I'm not entirely sure as it's not a very common or well - known specific concept. It could potentially be a fan - made story where Naruto has some sort of connection or admiration for the Phenex, perhaps in a crossover or alternate universe scenario.
The main themes can vary widely. But often there is the theme of adaptation. Since she is in the High School DxD world, she has to adapt to different situations. Love is also a theme sometimes, whether it's romantic love or love for her comrades. And there's the theme of destiny, like what her true purpose is in this fictional universe which is full of magic, power struggles and various factions.
Well, if Naruto had the Phenex power and could use Amaterasu in the Susanoo, it would be an insanely powerful combination. The Phenex power might enhance the already intense Amaterasu flames within the Susanoo. Naruto's chakra control would play a huge role in how he wields this newfound power. He could potentially use it to create massive destruction or for defensive purposes, like creating a shield of super - hot Amaterasu - laced Susanoo around himself or his allies.
One possible fanfiction could be about a character with the powers of Phenex in the Naruto universe. They might use their unique abilities in combination with Naruto's own powers, like the Rasengan. When it comes to Amaterasu and Susanoo, perhaps this new character has to face off against an enemy who wields these powerful Uchiha abilities. The story could explore how the Phenex powers interact with the chakra - based abilities in Naruto's world, whether they enhance or conflict with each other.
Then there could be a Phenex clan member as a main character, perhaps a young Phenex who is on a journey and crosses paths with Naruto. This Phenex character could have unique abilities like fire manipulation and regeneration, which are typical of the Phenex in some fanon interpretations. They could befriend Naruto or start off as rivals.
One idea could be that Lady Death, being a powerful entity from another realm, senses Naruto's strong will and unique chakra. She decides to visit the Naruto universe to observe him closely. Naruto, initially confused by her presence, soon realizes she has knowledge that could help him become even stronger. They form an unlikely alliance where Naruto learns new skills from Lady Death, which he then uses to protect his village in a new and unexpected way.
Since I haven't read this particular fanfiction, it's hard to say exactly. However, based on the title, it seems that it could be a story where the concept of the Phenex, which might be some kind of powerful or special entity in the fanfiction, has a forgotten hierarchy in the Naruto universe. This forgotten hier might be rediscovered by a character, perhaps Naruto himself or someone close to him. It could lead to all sorts of adventures, power struggles, and revelations as the character delves deeper into the secrets of the Phenex hier.
I really liked 'The Phenex Legacy in Naruto'. In this fanfiction, the concept of Azure Phenex is blended with the ninja world's lore. It shows how the power of Azure Phenex can change the power dynamics in battles. The story also delves into the backstory of the character related to Azure Phenex, which makes it more engaging.